So. After Poke came out, everything looked great for Facebook for a few days.

Facebook pushed distribution of Poke through its already massive installed Facebook iOS app, and Poke quickly shot to number one in Apple’s iTunes App Store.

At this point, Facebook PR seemed to hang up a “Mission Accomplished” banner of sorts in the press. Stories leaked that Facebook built the app in only 12 days. Another report surfaced that Mark Zuckerberg himself had worked on the app – that he voiced the sound that Poke’s iOS push notification makes. People started talking about the end of Snapchat.

But then something funny started happening.

Poke started dropping in the iTunes rankings. It sank to 34th. Then to 39. Now it’s down to 50. Snapchat, meanwhile, remains the third most popular app in the store.

And now, instead of writing stories about how Snapchat is doomed, people are wondering: What’s wrong with product development at Facebook?

The many questions boil down to two specific ones:

Why is Facebook innovation so bad that it has to copy products from smaller startups? Facebook has a long history of copying smaller startups. At various points, it has cloned features from: Instagram, Twitter, Quora, Foursquare, Groupon, and Yelp.

Why can’t Facebook seem to rip off startups that well? Everyone thought Facebook would kill Instagram, Twitter, Quora, Foursquare, Groupon, and Yelp with those products. It did not. At all.

The really scary thing for Facebook is that Poke’s failure might reveal a problem that actually goes deeper than its product development team.

“Is Facebook’s app platform, clearly its biggest innovation to date, a bust? Why hasn’t there been a second Zynga-like company that has been built on the Facebook app platform? Wasn’t there supposed to be a Zynga in a dozen different verticals? What happened to the ‘social operating’ system?”

Here is the point Calacanis and Malik are getting at – one that should really worry Facebook: Maybe Poke’s failure isn’t about flaws in Facebook’s product ideation or product-building.